Field of the Invention
The present invention relates to a circuit configuration and to a method for a voltage supply for electric function units which includes a plurality of circuit elements and are supplied with voltage from a central voltage source. In particular, the invention relates to supplying direct voltage to mobile phones.
In function units, such as mobile phones, that include a plurality of circuit elements, there is often a need to reduce the operating voltage of the particular function unit, for instance so that smaller, lighter batteries can be used. Reducing the operating voltage, however, can lead to manifold problems with the individual circuit elements.
In mobile phones, 3-volt batteries are often used now, instead of the 6-volt or 12-volt voltage supply that was previously conventional. This reduction in operating voltage can lead to a number of problems with individual circuit elements, depending on the construction and the operating state. Reducing the operating voltage means that individual circuit elements can be overridden and thus are no longer operated in the linear range.
Because of the higher current consumption, buffer capacitors must also be made larger, which in turn runs counter to the trend toward miniaturization. Finally, higher currents in general lead to higher line losses. Another considerable disadvantage may be the disproportionately increased noise vulnerability in frequency modulation. Reducing the supply voltage from 12 V to 3 V, at a maximum voltage rise of 2 V and a tuning range of 75 MHz, for instance, leads to modulation and interference sensitivity increased by a factor of 10.
From Published International Patent Disclosure WO A 96 03 811, a circuit configuration for a voltage supply to supply a plurality of circuit elements is known. Between a central voltage source and the circuit elements, a device is connected that converts a voltage supplied from the central voltage source into a circuit-element-individual voltage and delivers that voltage to the circuit elements.